# Relative motion with cart and ball

• ryan1180
In summary, a cart with a velocity of 10 m/s in the horizontal direction ejects a ball with an initial velocity vB with respect to the cart. The ball moves vertically and reaches its maximum height after 2 seconds. The angle θ, as measured by someone on the cart, is less than 90 degrees. The magnitude of vB can be calculated using the formula vB = vBC + vCG, and the correct answer is 10 m/s.
ryan1180

## Homework Statement

A cart moves with velocity vC = 10 m/s in the horizontal direction as shown below.

[PLAIN]https://online-s.physics.uiuc.edu/cgi/courses/shell/common/showme.pl?courses/phys100/fall10/hwb/04/01/cart.gif

A ball is ejected from the cart with an initial velocity vB with respect to the cart such that an observer on the ground sees the ball move directly vertical. The ball reaches its maximum height at a time t = 2 s after it is launched. The next two questions pertain to this situation.

1) The angle θ (as measured by someone on the cart) is greater than 90 degrees.

(True or False)

2) What is vB, the magnitude of the initial velocity of the ball with respect to the cart?

vB = 10 m/s
vB = 18 m/s
vB = 22 m/s
vB = 26 m/s
vB = 30 m/s
(multiple choice)

vB=vBC+vCG

## The Attempt at a Solution

I'm pretty sure that the answer to part 1 is false

For part 2 I think the answer is 10, but I get confused with relative motion...

Last edited by a moderator:
Am I at least using the correct formula for this? I'm not even sure about that...

## 1. What is relative motion?

Relative motion refers to the movement of one object in relation to another object. It takes into account the position, speed, and direction of both objects to determine their relative motion.

## 2. How is relative motion different from absolute motion?

Absolute motion is the movement of an object in relation to a fixed point or reference frame, while relative motion considers the movement of an object in relation to another object. Absolute motion is constant and does not change, while relative motion is dependent on the perspective of the observer.

## 3. How does the cart and ball experiment demonstrate relative motion?

In the cart and ball experiment, the ball is placed on top of a cart that is moving at a constant speed in a straight line. From the perspective of someone on the ground, the ball appears to be moving in a curved path. However, from the perspective of someone on the cart, the ball appears to be moving in a straight line. This demonstrates how the relative motion of the ball changes depending on the observer's perspective.

## 4. What factors can affect relative motion?

The relative motion between two objects can be affected by their speed, direction, and distance from each other. Other factors such as friction, air resistance, and external forces can also impact relative motion.

## 5. Why is understanding relative motion important in science?

Understanding relative motion is important in science because it allows us to accurately describe the movement of objects and predict their future positions. It is also crucial in fields such as physics and engineering, where precise calculations and measurements of relative motion are necessary for various applications.

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